The present invention relates to an apparatus for controlling the operation of a refrigerator and, more particularly, to an apparatus for controlling the operation of a refrigerator incorporated in an air conditioning system installed in a building or the like.
In the air conditioning systems installed in a building or the like, the temperature of the cold water cooled by the refrigerator is determined from the view point of the capacity of the installation. Namely, the capacities of the water pump, blower and other devices, as well as the heat transfer area of the heat exchanger, can be reduced as the difference of temperature between the cold water cooled by the refrigerator and the high temperature in the store or room is increased. Thus, the set temperature of the cold water should be selected to be the lower limit afforded by the refrigerator, in order to minimize the installation cost.
In the conventional air conditioning systems, the refrigerator is operated such that the cold water outlet temperature or the cold water inlet temperature always coincides with the above-mentioned set temperature. Such a method of operating refrigerator is shown, for example, at page 80 in "ABSORPTION REFRIGERATOR AND ITS APPLICATION", published from Association of Refrigeration of Japan (corporation). According to this operation method, the temperature difference between the cold water and the high-temperature source is maintained constant irrespective of the refrigeration load. Therefore, when the refrigeration load is reduced to a level below the rated load, i.e., during partial load operation, the heat through the heat exchanger is reduced to conform with the refrigeration load, by reducing the flow rate of the water or air by controlling the operation of the water pump or blower, or by changing the heat transfer area of reducing the number of heat exchangers taking part in the operation.
From a view point of the efficiency of the system as a whole, it is desirable that the temperature of the cold water is raised during the partial load operation. Thus, the above-explained conventional method in which the temperature of the cold water is maintained constant is not preferred from this point of view. Namely, in this conventional method, the coefficient of performance is lowered because the temperature of the cold water is maintained unnecessarily low, so that the refrigerator has to consume greater energy for a given refrigeration load.
Thus, in the conventional operation method, the running cost of the air conditioning system is increased due to the low coefficient of performance of the refrigerator.